Physical random access channel (prach) receiver for determining cells in which a preamble has been transmitted

Abstract

A method ( 300 ) for determining cells in which a preamble has been transmitted. The method includes obtaining (s 302 ) N sample sets, wherein each one of the N sample sets comprises a set of M samples and each one of the N sample sets is associated with a different cell included in a set of N cells. The method also includes adding (s 304 ) the N sample sets to create a first combined set of samples comprising M samples. The method also includes forming (s 306 ) a first candidate set of one or more tuples based on the first combined set of samples and an initial set of tuples comprising a plurality of tuples, wherein each tuple comprises a candidate preamble and a candidate delay, and wherein each candidate preamble comprises a set of samples. The method further includes using (s 308 ) the first candidate set of one or more tuples to determine, for each cell included in the set of cells, whether a preamble included in the first candidate set of tuples was transmitted in the cell.

1 . A method for determining cells in which a preamble has been transmitted, the method comprising:
 obtaining N sample sets, wherein each one of the N sample sets comprises a set of M samples and each one of the N sample sets is associated with a different cell included in a set of N cells;   combining the N sample sets to create a first combined set of samples comprising M samples;   forming a first candidate set of one or more tuples based on the first combined set of samples and an initial set of tuples comprising a plurality of tuples, wherein each tuple comprises a candidate preamble and a candidate delay, and wherein each candidate preamble comprises a set of symbols; and   using the first candidate set of one or more tuples to determine, for each cell included in the set of cells, whether a preamble included in the first candidate set of tuples was transmitted in the cell.   
     
     
         2 . The method of  claim 1 , wherein forming the first candidate set of one or more tuples comprises:
 for each tuple included in the initial set of tuples, removing the tuple from the initial set of tuples as a result of determining that the tuple does not match the first combined set of samples, thereby forming the first candidate set of one or more tuples, or   for each tuple included in the initial set of tuples, adding the tuple to the first candidate set of tuples as a result of determining that the tuple matches the first combined set of samples, thereby forming the first candidate set of one or more tuples.   
     
     
         3 . The method of  claim 1 , wherein using the first candidate set of one or more tuples to determine, for each cell included in the set of cells, whether a preamble included in the first candidate set of tuples was transmitted in the cell comprises:
 forming a first subset of the N sample sets;   combining the first subset of the N sample sets to create a second combined set of samples comprising M samples;   forming a second candidate set of tuples based on the second combined set of samples and the first candidate set of tuples; and   using the second candidate set of tuples to determine, for each cell associated with one of the sample sets included in the first subset of sample sets, whether a preamble included in the second candidate set of tuples was transmitted in the cell.   
     
     
         4 . The method of  claim 3 , wherein forming the second candidate set of one or more tuples comprises:
 for each tuple included in the first candidate set of tuples, removing the tuple from the first candidate set of tuples as a result of determining that the tuple does not match the second combined set of samples, thereby forming the second candidate set of one or more tuples, or   for each tuple included in the first candidate set of tuples, adding the tuple to the second candidate set of tuples as a result of determining that the tuple matches the second combined set of samples, thereby forming the second candidate set of one or more tuples.   
     
     
         5 . The method of  claim 3 , wherein using the first candidate set of one or more tuples to determine, for each cell included in the set of cells, whether a preamble included in the first candidate set of tuples was transmitted in the cell further comprises:
 forming a second subset of the N sample sets;   combining the second subset of the N sample sets to create a third combined set of samples comprising M samples;   forming a third candidate set of tuples based on the third combined set of samples and the first candidate set of tuples; and   using the third candidate set of tuples to determine, for each cell associated with one of the sample sets included in the second subset of sample sets, whether a preamble included in the third candidate set of tuples was transmitted in the cell.   
     
     
         6 . The method of  claim 5 , wherein forming the third candidate set of one or more tuples comprises:
 for each tuple included in the first candidate set of tuples, removing the tuple from the first candidate set of tuples as a result of determining that the tuple does not match the third combined set of samples, thereby forming the third candidate set of one or more tuples, or   for each tuple included in the first candidate set of tuples, adding the tuple to the third candidate set of tuples as a result of determining that the tuple matches the third combined set of samples, thereby forming the third candidate set of one or more tuples.   
     
     
         7 . The method of  claim 5 , wherein the second subset of the N sample sets is disjoint with the first subset of the N sample sets. 
     
     
         8 . The method of  claim 1 , wherein using the first candidate set of one or more tuples to determine, for each cell included in the set of cells, whether a preamble included in the first candidate set of tuples was transmitted in the cell comprises:
 for each cell included in the set of cells, determining whether the sample set corresponding to the cell matches one or more of the tuples included in the first candidate set of tuples.   
     
     
         9 . The method of  claim 1 , wherein combining the N sample sets to create a first combined set of samples comprising M samples comprises calculating: S11+S21+ . . . +SN1, where
 S11 is a first sample within a first one of the N sample sets,   S21 is a first sample within a second one of the N sample set, and   SN1 is a first sample within the Nth one of the N sample sets.   
     
     
         10 . The method of  claim 1 , wherein combining the N sample sets to create a first combined set of samples comprising M samples comprises calculating: (p1*S11)+(p2*S21)+ . . . +(pN*SN1), where
 S11 is a first sample within a first one of the N sample sets,   S21 is a first sample within a second one of the N sample set,   SN1 is a first sample within the Nth one of the N sample sets,   pi for i=1 to N is a determined factor for the i-th cell.   
     
     
         11 . A non-transitory computer readable storage medium storing a computer program comprising instructions which when executed by processing circuitry of a preamble detector, causes the preamble detector to perform the method  claim 1 . 
     
     
         12 . (canceled) 
     
     
         13 . A preamble detector, the preamble detector comprising:
 processing circuitry; and   a memory, the memory containing instructions executable by the processing circuitry, whereby the preamble detector is configured to perform a method comprising:   obtaining N sample sets, wherein each one of the N sample sets comprises a set of M samples and each one of the N sample sets is associated with a different cell included in a set of N cells;   adding the N sample sets to create a first combined set of samples comprising M samples;   forming a first candidate set of one or more tuples based on the first combined set of samples and an initial set of tuples comprising a plurality of tuples, wherein each tuple comprises a candidate preamble and a candidate delay, and wherein each candidate preamble comprises a set of samples; and   using the first candidate set of one or more tuples to determine, for each cell included in the set of cells, whether a preamble included in the first candidate set of tuples was transmitted in the cell.   
     
     
         14 - 15 . (canceled) 
     
     
         16 . The preamble detector of  claim 13 , wherein forming the first candidate set of one or more tuples comprises:
 for each tuple included in the initial set of tuples, removing the tuple from the initial set of tuples as a result of determining that the tuple does not match the first combined set of samples, thereby forming the first candidate set of one or more tuples, or   for each tuple included in the initial set of tuples, adding the tuple to the first candidate set of tuples as a result of determining that the tuple matches the first combined set of samples, thereby forming the first candidate set of one or more tuples.   
     
     
         17 . The preamble detector of  claim 13 , wherein using the first candidate set of one or more tuples to determine, for each cell included in the set of cells, whether a preamble included in the first candidate set of tuples was transmitted in the cell comprises:
 forming a first subset of the N sample sets;   combining the first subset of the N sample sets to create a second combined set of samples comprising M samples;   forming a second candidate set of tuples based on the second combined set of samples and the first candidate set of tuples; and   using the second candidate set of tuples to determine, for each cell associated with one of the sample sets included in the first subset of sample sets, whether a preamble included in the second candidate set of tuples was transmitted in the cell.   
     
     
         18 . The preamble detector of  claim 17 , wherein forming the second candidate set of one or more tuples comprises:
 for each tuple included in the first candidate set of tuples, removing the tuple from the first candidate set of tuples as a result of determining that the tuple does not match the second combined set of samples, thereby forming the second candidate set of one or more tuples, or   for each tuple included in the first candidate set of tuples, adding the tuple to the second candidate set of tuples as a result of determining that the tuple matches the second combined set of samples, thereby forming the second candidate set of one or more tuples.   
     
     
         19 . The preamble detector of  claim 17 , wherein using the first candidate set of one or more tuples to determine, for each cell included in the set of cells, whether a preamble included in the first candidate set of tuples was transmitted in the cell further comprises:
 forming a second subset of the N sample sets;   combining the second subset of the N sample sets to create a third combined set of samples comprising M samples;   forming a third candidate set of tuples based on the third combined set of samples and the first candidate set of tuples; and   using the third candidate set of tuples to determine, for each cell associated with one of the sample sets included in the second subset of sample sets, whether a preamble included in the third candidate set of tuples was transmitted in the cell.   
     
     
         20 . The preamble detector of  claim 19 , wherein forming the third candidate set of one or more tuples comprises:
 for each tuple included in the first candidate set of tuples, removing the tuple from the first candidate set of tuples as a result of determining that the tuple does not match the third combined set of samples, thereby forming the third candidate set of one or more tuples, or   for each tuple included in the first candidate set of tuples, adding the tuple to the third candidate set of tuples as a result of determining that the tuple matches the third combined set of samples, thereby forming the third candidate set of one or more tuples.   
     
     
         21 . The preamble detector of  claim 19 , wherein the second subset of the N sample sets is disjoint with the first subset of the N sample sets. 
     
     
         22 . The preamble detector of  claim 13 , wherein using the first candidate set of one or more tuples to determine, for each cell included in the set of cells, whether a preamble included in the first candidate set of tuples was transmitted in the cell comprises:
 for each cell included in the set of cells, determining whether the sample set corresponding to the cell matches one or more of the tuples included in the first candidate set of tuples.   
     
     
         23 . The preamble detector of  claim 13 , wherein combining the N sample sets to create a first combined set of samples comprising M samples comprises calculating: S11+S21+ . . . +SN1, where
 S11 is a first sample within a first one of the N sample sets,   S21 is a first sample within a second one of the N sample set, and   SN1 is a first sample within the Nth one of the N sample sets.